A large explosion killed at least eight people and injured dozens more in the Lebanese capital of Beirut today, local officials said.

Video and still images from the scene show confusion and chaos, with emergency sirens blaring and many people -- some with blood stains on their clothes -- walking through rubble in the streets.

Lebanese state media reported the explosion appeared to be caused by a car bomb, and photos posted online appear to show the remains of one vehicle that was completely mangled and burned out. The explosion occurred during rush hour.

One journalist on the scene told ABC News she saw "loads of body parts" and part of a car lodged into nearby buildings. Glass was shattered everywhere, she said. The explosion took place in the heart of east Beirut, but was felt clear across the city, another witness said.

No group has publicly taken credit for the attack. One Lebanese politician reportedly told a local television station it was similar to past bombings blamed on the Syrian regime, but the Syrian government quickly condemned the act.

Col. Wissam al-Hassan, an anti-Syrian senior Lebanese intelligence official, was killed in Friday's blast in Beirut. Al-Hassan's death was first reported by local media and confirmed to ABC News by a high-level Lebanese security official.

Al-Hassan was a central figure in the investigation into the 2005 assassination of former Prime Minister Hariri that largely pointed fingers at the Syrian regime. He also uncovered in August an alleged plot by a prominent Lebanese politician allied with the Syrian regime to plant bombs and carry out political assassinations in Lebanon.